This invention relates to apparatus and methods for monitoring and evaluating manufacturing operations which produce an ongoing stream of discrete absorbent articles effective to absorb body fluids. Such products are typically fabricated as a sequence of work pieces on a continuous web. Such absorbent articles generally comprise an absorbent core confined between a moisture impervious baffle of e.g. polyethylene and a moisture pervious body side liner of e.g. non-woven fibrous material. The absorbent articles are made by advancing one of the webs along a longitudinally extending path, applying the absorbent core to a first one of the webs, and then applying the second web. Other elements such as elastics, leg cuffs, containment flaps, waste bands, and the like are added as desired for the particular product being manufactured, either before or after applying the second web. Such elements may be oriented longitudinally along the path, or transverse to the path, or may be orientation neutral.
Upon the occurrence of certain events, the products fabricated by such manufacturing operations may be moving out of a tolerance range of predetermined required specifications whereupon corrective action should be taken in the manufacturing operation; or the product may fall outside such specifications and should be culled from the product stream.
A variety of possible events in the manufacturing operation can cause the production of absorbent articles which fall outside the specification range. For example, stretchable materials can be stretched less than, or more than, desired. Elements can become misaligned relative to correct registration in the manufacturing operation. Timing between process steps, or speed of advance of an element, can be slightly out-of-tolerance. If such non-catastrophic changes in process conditions can be detected quickly enough, typically process corrections can be made, and the variances from target reduced, without having to shut down the manufacturing operation and without having to cull, and thereby waste, product.
Certain events, however, inherently result in production of out-of-tolerance product whereby no amount of process control can avoid product culling. Exemplary of such events are splices in the base continuous web.
Where product is outside the specification range, and should be culled, it is desired to cull all defective product, but only that product which is in fact defective. If too little product is culled, or if the wrong product is culled, then defective product is inappropriately released into the stream of commerce. If product which in fact meets product specification is culled, the good product is being wasted.
Body fluid absorbing absorbent articles are typically manufactured at speeds of about 50 to about 1200 articles per minute on a given manufacturing line. Accordingly, it is impossible for an operator to hand inspect each and every article so produced. If the operator reacts conservatively, culling product every time he/she has a suspicion, but no solid evidence, that some product may not meet specification, then a significant amount of in fact good product will have been culled. However, if the operator takes action only when a defect has been confirmed using visual inspection, defective product may already have been released into the stream of commerce.
One way for the operator to inspect the product for conformity with the specification range is for the operator to periodically gather and inspect, off-line, physical samples of the product being produced. Random such inspections stand little prospect of detecting temporary out-of-specification conditions. Where such samples are taken in response to a suspected out-of-specification condition, given the high rate of speed at which such articles are manufactured, by the time the operator completes his/her inspection, the suspected offensive condition may have existed long enough that questionable product will have either been shipped or culled without the operator having any solid basis on which to make the ship/cull decision. Further, automated manufacturing process controls may have self-corrected the defect condition before the operator can complete the visual inspection and act on the results of such visual inspection.
While off-line inspection is the primary determinant of quality, and defines the final quality and disposition of the product, on-line inspection, and off-line inspection of on-line-collected data, typically associated with certain manufacturing events, may provide valuable insight into both the operation characteristics of the manufacturing process, and the final quality parameters of the product.
Recent advances in product inspection include use of one or more vision imaging systems having a camera disposed along the path of manufacture. A vision imaging system camera can thus be placed in a fixed location, for collecting visual images of the product at that location. The vision imaging system continuously collects images of the product work pieces as the product precursors pass the point in the manufacturing process which is being monitored. The images so collected are transmitted to a visual display device such as a video monitor at the operator""s station, whereby the operator can visually monitor certain visual parameters of the product at the respective location along the manufacturing path.
Such vision imaging systems typically run continuously during manufacturing operations, such that the operator can continuously, or at any time, monitor the condition of the product being manufactured at the given location in the manufacturing line. However, conventional continuous-duty vision imaging systems do not provide any mechanism for the operator to archive any images being viewed.
Some current vision imaging systems can be used to instantaneously capture the full digital representation of a vision image, and to capture and transfer measurement data representing limited portions of each of the images to be evaluated, but have very limited ability to store or transfer full visual images related to that data. The memory storage capacity of such vision imaging systems provides a limited capacity for temporarily or permanently storing vision images so collected. The collected images and data can be transferred to permanent storage within the vision imaging systems, but the imaging system has very limited capacity to permanently store the images, and such permanent storage will compromise the ability to continue collecting data while simultaneously transferring collected data to permanent storage at the production speeds contemplated here of, for example and without limitation, at least 200 inspections per minute.
The capacity to simultaneously collect data, and transfer data to permanent storage, is a function of both the complexity of the inspection of images being captured and analyzed, and the frequency with which images are to be captured. At typical manufacturing speeds for manufacturing absorbent articles such as diapers and incontinence products, namely at least 300-400 units per minute, current vision imaging systems are unable to sustain required rates of ongoing simultaneous capture and transfer of the images available for capture at the rate of one image per unit of production.
Removal or transfer of the data, and restarting of the collection process in such existing vision imaging system typically includes operator intervention, but can be done by pre-programmed computer control. While limited amounts of data can thus be collected and archived from a high speed operation such as illustrated in the drawings, the amount of data which can be collected relating to a given event is quite limited. Typically, current imaging systems will freeze on the first defective image detected. Restarting of the collection process can be pre-programed and thus computer controlled, or can be manual. Accordingly, to the extent the ongoing manufacturing process is producing data that could be useful to the operation and/or analysis of the process, current imaging systems have very limited capability to collect, archive, and then reconstruct vision images of such data. While a limited set of measurement data from such images can be archived, and retrieved, such data is insufficient for reconstructing the desired vision images.
Other vision imaging systems such as KODAK(copyright) EKTAPRO(copyright) Model 1012 Motion Analyzer can be used to capture full visual images but not to automatically generate measurement data. Such a vision imaging system can collect and display real-time video images, and can store up to 1637 of the most recent frames of video images in memory. The images can be synchronized with the manufacturing operation such that each frame/image shows and represents each successive work piece. However, such a portable systems is unsuited for continuous duty operation, and is unable to retain in storage any but the latest 1637 frames. The stored images can be downloaded to a limited number of models of VCR, but camera recording cannot take place concurrently with the downloading to the VCR. Thus, where a particular set of images is of interest, such images are lost as soon as additional images, greater than the 1637 frames, are taken, or camera recording must be stopped in order to download the images to a VCR. However, as indicated above, the KODAK EKTAPRO system does not, of itself, generate measurement data related to such images without manual intervention.
Accordingly, current systems are unable to automatically and simultaneously capture and transfer both the full digital image and the desired selected measurement data, to permanent storage. Thus, the user is torn between the need to retain certain information which may be valuable for later analysis and the need to continue monitoring the real-time images of the articles being currently produced in the manufacturing operation.
Thus, it is desirable to provide quality control process and/or apparatus capable of both monitoring the real-time condition of the articles being manufactured, and simultaneously capable of selectively archiving certain sets of the visual image data in a memory storage device.
It is further desirable to archive in memory storage only that data which provides an above average probability of containing information of interest for maintaining quality control or for engineering development.
Accordingly, it is desirable to send visual image information to memory storage only upon the occurrence of one or more triggering events related to the manufacturing operation and while camera image recording is continued.
It is desirable that, upon occurrence of the triggering event, the apparatus and/or process automatically sends preselected ones of the images to memory storage as visual image information.
It is desirable that, during the time wherein visual image information is being sent to storage, the visual image display be continued uninterrupted and undisturbed, selecting and displaying images without being affected by the fact that visual images are being transferred to data storage.
It is still further desirable to provide such quality control process and/or apparatus wherein the visual display continues unabated before, during, and after, sending visual images to storage.
It is yet further desirable to provide such quality control process and/or apparatus which first sends the visual image information, to be stored, to a high speed temporary memory storage device at a rate of about 300 to about 1000 visual images per minute, and from the high speed temporary memory storage device, writes the visual image information to a slower speed, but larger capacity permanent memory storage device.
It is further desirable to provide such quality control process and/or apparatus which can continue manufacturing absorbent articles while collecting and displaying a continuous real-time display of the visual images so collected, and which can send at least two sets of visual images to storage at periods spaced in time sufficient to allow the high-speed temporary storage to write the entirety of the first set of images to the permanent storage without interference from the second set.
It is still further desirable to provide such quality control process and/or apparatus including placing identifying information on physical work pieces represented by the visual image information so stored, thus to enable correlation of specific work pieces or absorbent article products with specific visual images so stored.
It is highly desirable to suspend image storage, and to store few if any of such images after completion of any one predefined set of visual images, until occurrence of the next triggering event.
It is still further desirable, in some instances, to collect such visual images at two or more fixed locations along the path of manufacturing operations, in response to triggering events.
It is thus an object of the invention to provide quality control process and/or apparatus capable of both monitoring the real-time condition of the articles being manufactured, and simultaneously capable of selectively archiving certain sets of the visual image data in a memory storage device.
It is another object to archive in memory storage only that data which provides an above average probability of containing information of interest for maintaining quality control or for engineering development.
It is still another object to send image information, preferably as digital data, to memory storage only upon the occurrence of one or more triggering events related to the manufacturing operation and while camera image recording is continued.
It is a further object that, upon occurrence of the triggering event, the apparatus and/or process automatically sends preselected ones of the images to memory storage as visual image information.
It is a yet further object that, during the time wherein visual image information is being sent to storage, the visual image display be continued uninterrupted and undisturbed, selecting and displaying images without being affected by the fact that visual images are being transferred to data storage.
It is a still further object to provide such quality control process and/or apparatus wherein the visual display continues unabated before, during, and after, sending visual images to storage.
It is yet a further object to provide such quality control process and/or apparatus which first sends the visual image information to be stored to a high speed temporary memory storage device at a capacity rate of at least about 300 to about 1000 visual images per minute, and from the high speed temporary memory storage device, writes the visual image information to a slower speed, but larger capacity permanent memory storage device.
It is further an object to provide such quality control process and/or apparatus which can continue manufacturing absorbent articles while collecting and displaying a continuous real-time display of the visual images so collected, and which can send at least two sets of visual images to storage at periods spaced in time sufficient to allow the high-speed temporary storage to write the entirety of the first set of images to the permanent storage without interference from the second set.
It is still a further object to provide such quality control process and/or apparatus including placing identifying information on digital images of specified work pieces, thus to enable correlation of specific work pieces or absorbent article products.
It is yet another object to suspend image storage, and to store few if any of such images after completion of any one predefined set of visual images, until occurrence of the next triggering event.
A still further object is to collect such visual images at two or more fixed locations along the path of manufacturing operations, in response to triggering events.
Some of the objects are achieved in a first family of embodiments of the invention comprehending a method of using a vision imaging system in a manufacturing operation wherein the manufacturing operation produces an ongoing stream of discrete absorbent article work pieces and products made therefrom, effective to absorb body fluids. The method produces such absorbent articles on a continuous web, and comprises operating a vision imaging system which collects visual images at one or more generally fixed locations in the manufacturing operation, typically collecting discrete visual images at a rate of at least 50 images per minute, preferably but without limitation up to about 1200 images per minute, at each fixed location, preferably at least about 200 up to about 1000 images per minute, more preferably at least about 300 images per minute, still more preferably at least about 400 up to about 900 images per minute, and most preferably about 600 up to about 800 images per minute. The method further provides an ongoing visual image display of a pattern of successive such images so collected, each such visual image representing a successive at least one of a workpiece or a product, or a process condition, associated with the manufacturing operation. The method further comprises selecting one or more triggering events, planned or unplanned, related to the manufacturing operation, and upon occurrence of any one of the triggering events, continuing the ongoing visual display of the pattern of images, typically at substantially the same image collection rate, while concurrently sending data representing a limited number set of such real-time visual images so collected, to a memory storage device. Such memory device should be a high-speed memory device such as a digital memory device, for example a relatively high-capacity random-access memory device or a buffer memory device. The image collection rate can be adjusted as needed at any time, including while image data is being transferred from temporary storage to permanent storage.
The method preferably includes sending to the memory storage device at least some of the same visual images as are displayed on the image display device.
The method preferably includes, upon conclusion of the sending of the set of images to the digital memory device, continuing the ongoing collection of visual images and thereby continuing to provide an ongoing real-time visual image display of the pattern of images representing at least one of the work piece or product, or the process.
In preferred embodiments, the method includes writing the visual image data from the memory storage device to a second, slower speed, higher capacity, memory storage device.
The method preferably includes synchronizing the collection of images such that each subsequent image so collected shows a full length and a full width of one such workpiece or product, or one such process condition, per frame and one visual frame per workpiece or product, or process condition. Preferably, sequential images represent sequential work pieces or products, or sequential process conditions.
Preferred such methods include, while sending the set of visual images to the storage device, using computer logic to analyze, in real time, the visual images so collected, and sending corresponding results signals to control apparatus controlling the manufacturing operation, and the control apparatus processing the results signals and, based on the processing of such results signals, issuing control commands to thereby modify the manufacturing operation. Such control command can, for example, modify timing of a process step, or result in culling work pieces from the manufacturing operation.
In some embodiments, the control command stops the manufacturing operation. In such embodiments, when the required condition is detected on the manufacturing line, process control logic issues a command to generate e.g. a stop signal. The stop signal activates a sequence in the software that enables the process to shutdown e.g. through electronic and/or mechanical braking means or withdrawal of driving power. The required condition can be triggered via automated sensor or operation intervention. In some embodiments, the control command provides an alarm to an operator.
The method can optionally include continuing to run the manufacturing operation upon conclusion of the sending of the set of visual images to the memory storage device, and while so continuing to run the manufacturing operation, sending a second set of a second limited number of real-time visual images, which number may or may not be the same as the number of images in the first set, to the e.g. digital memory storage device in response to a second triggering event.
The method can include incorporating identifying information with the stored full digital image information representing the work pieces, thus to enable correlation of specific images so stored with specific work pieces.
The method preferably includes, after completion of the sending of the set of real-time visual images and prior to occurrence of a second triggering event, sending to the digital memory storage device few or none of the real-time visual images being collected.
Preferred embodiments of the method preferably comprehend storing the images in digital format, including maintaining substantially full digital integrity of the visual images so stored, compared with the images as collected, thereby to enable substantially full visual reproduction of the visual images so stored.
In some embodiments, the recited fixed location comprises a first fixed location, the set of visual images comprises a first set of visual images, and the method includes collecting visual images at a second generally fixed location in the manufacturing operation, in response to a triggering event, and sending a limited-number second set of real-time visual images so collected to the digital memory, and optionally including segregating the first and second sets of visual images from each other in the memory storage device.
The triggering event which triggers sending the second set of images to memory may be the same triggering event that triggers sending the first set of images to memory. Sending the second set of images to memory storage may occur concurrently with sending the first set of images to memory storage, in part concurrently, or subsequent to completion of sending the first set of images to memory storage.
The invention further comprehends apparatus for capturing, and concurrently displaying and storing in memory, visual images of a process which manufactures absorbent articles effective to absorb body fluids. The apparatus comprises manufacturing machines manufacturing such absorbent articles, the machines including control apparatus effective to control operations of the manufacturing machines so as to fabricate such absorbent articles according to predetermined parameters; a vision imaging system collecting real-time discrete visual images at a generally fixed location in association with the manufacturing machines, of a work piece or a product, or a process condition, associated with the absorbent articles being produced, and presenting a real-time visual image display of the images so collected, on an image display device, and sending corresponding results signals to the control apparatus, thereby to control the manufacturing machines; and a memory storage system receiving a limited-number set of the real-time visual images, substantially less than the entirety of all the visual images so collected and displayed by the vision imaging system.
In preferred apparatus, the memory storage system comprises a high-speed temporary memory storage device, and a permanent memory storage device receiving the stored images from the temporary memory storage device.
The memory storage system preferably receives the set of visual images concurrent with the display of real-time images on the display device. Preferably, at least some of the visual images received in the memory storage system are the same images as are being concurrently displayed on the image display device.